时间贴现在神经和行为上的年龄特征

时间贴现的年龄发展具有阶段性。前额皮质, 边缘系统和多巴胺能系统的发展成熟是从儿童期到成人期时间贴现发展变化的神经生物基础。成人期到老年期时间贴现年龄特征的研究结果不一致。概率贴现、未来定向、延迟满足等被用来探讨时间贴现年龄发展特征。可以从大脑不同区域的发展轨迹, 延迟时段的心理意义来进一步深入研究。     

概率贴现和时间贴现在人脑中的分离

本研究运用ERP技术来检验概率贴现和时间贴现是否反映了相同的神经机制过程。在本研究中,我们在一个刺激中同时操纵概率贴现（风险vs.安全）和时间贴现（1个月后vs.今天）水平。通过对两个过程上的ERN以及全时间段的ERP分析来确定它们是否反映了相同的认知过程。结果发现,这两者在ERN上存在差异,同时这两个效应在ERP的时程和出现的电极点上都存在差异。这些差异表明这两者可能包含着不同的神经机制过程。     

时间洞察力对拖延行为的影响机制:时间折扣的中介作用

采用津巴多时间洞察力量表（ZTPI）、一般拖延量表（GPS）和跨期选择任务,考察了时间洞察力对拖延行为的影响,并从时间折扣视角检验了时间洞察力影响拖延行为的中介机制。结果表明（1）对553名大学生的测量数据进行逐步回归和优势分析,结果表明："未来"时间洞察力对拖延行为具有良好的预测力,解释率最高;（2）对121名大学生的测量数据进行中介分析,结果表明：时间折扣在时间洞察力影响拖延行为过程中起着中介作用。这些结果说明,"未来"时间洞察力对拖延行为具有较好的预测作用,而且未来时间洞察力对拖延行为的影响可能是通过时间折扣为中介实现的。     

拖延的决策模型

拖延是指尽管预见到该行为会带来不利后果,人们仍自愿推迟开始或完成某一计划好的行为。先前的研究对拖延的类型、影响因素、成因以及干预等方面进行了广泛的探讨,然而拖延的决策过程——"现在做还是以后做?"认知机制还非常不清楚。因此,本文提出拖延决策模型试图从三方面阐明"现在做还是以后做?"的决策机制:首先,拖延动机和不拖延动机的斗争是决定是否拖延的根本;其次,拖延动机的斗争可以进一步简化为任务负性过程和任务正性结果的权衡;最后,主动推迟任务使负性过程发生延迟折扣是拖延的核心目的。拖延决策模型不仅有助于探明拖延的核心认知机制,也能够帮助预测拖延行为的发生及解释各种影响因素的作用机制,因此未来的研究可以借此整合一个从拖延的核心发生机制到各种影响因素的理论系统。     

时间洞察力对跨期选择偏好的预测

利用津巴多时间洞察力问卷,采用跨期选择经典范式,考察“现在享乐型”和“未来定向型”两类时间洞察力个体在跨期选择上的偏好,从人格特质角度来探究跨期选择的认知机制。结果发现：(1)现在享乐定向组的延迟折扣率显著高于未来定向组;(2)未来定向组在时间洞察力量表“未来维度”得分与延迟折扣率显著负相关。这说明时间洞察力对个体延迟折扣率具有预测作用,支持了跨期选择的时间感知基础模型。     

Effects of acute and chronic flunitrazepam on delay discounting in pigeons

Delay to delivery of a reinforcer can decrease responding for that reinforcer and increase responding for smaller reinforcers that are available concurrently and delivered without delay; acute administration of drugs can alter responding for large, delayed reinforcers, although the impact of chronic treatment on delay discounting is not well understood. In this experiment, the effects of repeated administration of the benzodiazepine flunitrazepam were studied in 6 pigeons responding on one key to receive food that was delivered immediately and on a second key to receive a larger amount of food that was delivered following delays which increased across a single session. Pigeons responded predominantly for the large reinforcer when there were no delays and when delays were short; however, as delays increased, responding for the large reinforcer decreased. Acutely, flunitrazepam (0.32, 1.0 and 3.2 mg/kg) dose-dependently increased responding for the large reinforcer, shifting the discounting curve rightward and upward. Repeated administration of flunitrazepam (0.32, 1.0 and 3.2 mg/kg, each for six sessions, separated by one session during which vehicle was administered) did not markedly alter its effects on responding for the large reinforcer, indicating that the development of tolerance to this effect of flunitrazepam is modest under these conditions.     

Sub-Optimal Choice by Pigeons: Failure to Support The Allais Paradox

Pigeons show a preference for an alternative that provides them with discriminative stimuli (sometimes a stimulus that predicts reinforcement and at other times a stimulus that predicts the absence of reinforcement) over an alternative that provides them with nondiscriminative stimuli, even if the nondiscriminative stimulus alternative is associated with 2.5 times as much reinforcement (Stagner & Zentall, 2010). In Experiment 1 we found that the delay to reinforcement associated with the nondiscriminative stimuli could be reduced by almost one half before the pigeons were indifferent between the two alternatives. In Experiment 2 we tested the hypothesis that the preference for the discriminative stimulus alternative resulted from the fact that, like humans, the pigeons were attracted by the stimulus that consistently predicted reinforcement (the Allais paradox). When the probability of reinforcement associated with the discriminative stimulus that predicted reinforcement was reduced from 100% to 80% the pigeons still showed a strong preference for the discriminative stimulus alternative. Thus, under these conditions, the Allais paradox cannot account for the sub-optimal choice behavior shown by pigeons. Instead we propose that sub-optimal choice results from positive contrast between the low expectation of reinforcement associated with the discriminative stimulus alternative and the much higher obtained reinforcement when the stimulus associated with reinforcement appears. We propose that similar processes can account for sub-optimal gambling behavior by humans.     

Sharing with others and delaying for the future in preschoolers

This study explored age differences in preschoolers’ temporal and social discounting and the association of these abilities. Research indicates that 4-year-olds are sensitive to rewards of differing magnitude (Lemmon & Moore, 2007). However, it is unclear whether preschoolers are able to consider length of time when making a choice to delay (Mischel, Masters, & Grusec, 1969). In this study, 66, 3- and 4-year-olds were presented a delay of gratification task in which length of delay was manipulated. Additionally, they were given a sharing task in which they distributed toys between themselves, a friend, and another peer. Results suggested sensitivity to delay differences only in the oldest group. Furthermore, delay sensitivity was associated with sharing more preferred toys with friends compared to another peer, suggesting that favoring the “self” closer in time overlaps with favoring “another” who is closer socially.     

The ecological rationality of delay tolerance: insights from capuchin monkeys

Both human and non-human animals often face decisions between options available at different times, and the capacity of delaying gratification has usually been considered one of the features distinguishing humans from other animals. However, this characteristic can widely vary across individuals, species, and types of task and it is still unclear whether it is accounted for by phylogenetic relatedness, feeding ecology, social structure, or metabolic rate. To disentangle these hypotheses, we evaluated temporal preferences in capuchin monkeys, South-American primates that, despite splitting off from human lineage approximately 35 million years ago, show striking behavioural analogies with the great apes. Then, we compared capuchins’ performance with that of the other primate species tested so far with the same procedure. Overall, capuchins showed a delay tolerance significantly higher than closely related species, such as marmosets and tamarins, and comparable to that shown by great apes. Capuchins’ tool use abilities might explain their comparatively high preference for delayed options in inter-temporal choices. Moreover, as in humans, capuchin females showed a greater delay tolerance than males, possibly because of their less opportunistic foraging style. Thus, our results shed light on the evolutionary origins of self-control supporting explanations of delay tolerance in terms of feeding ecology.     

Timing of retirement: Including a delay discounting perspective in retirement models

This research examined the influence of delay and anticipated health and enjoyment on the amount of retirement savings sacrificed for early retirement. In addition to testing and supporting predictions that willingness to sacrifice retirement savings would be less with shorter delays to retirement, greater anticipated health, and greater anticipated enjoyment, an individual difference delay discounting measure derived from experimental studies was used to extend the Beehr, Glazer, Nielson, and Farmer’s (2000) model of retirement age. We predicted and found that oldest preferred retirement age related to personal characteristics, current work factors, future retirement factors, and individual differences in delay discounting, with greater delay discounting being associated with a younger preferred retirement age. Findings suggest that delay discounting is an important consideration in retirement planning and also highlight the significance that retirement expectations and being tired of work have in affecting one’s preferred retirement age.